Diameter and Temperature Dependences of Phonon-Drag Magnetothermopower in Bismuth Nanowires

Abstract

ABSTRACTWe present theoretical calculations of the phonon-drag contribution to the Nernst thermoelectric power Syx in Bismuth nanowires. We investigate the thermopower Syx with diameters L ranging from 22 to 900 nm at low temperatures (0.1 - 4.0 K) and high magnetic fields (up to 16 T). We find that the peak of thermopower Syx around 14.75 T exhibits the size effect in two different ways: for wires with L≥200 nm, the peak height increases with decreasing L; for wires with L<200 nm, on the other hand, the peak height rapidly decreases with decreasing L. The dependence is accounted for by considering the contributions of discrete quantized phonon modes. We also discuss the temperature dependence of Syx.